"Yes," Cramer replied, saying it's "because I think she has thought about the people who are not doing well in the country, and that is great."

Those remarks add another layer to this week's back-and-forth between the Massachusetts senator and the "Mad Money" host, who on Tuesday said Wall Street executives were telling him that her 2020 bid has "got to be stopped."

Warren, whose steady rise in the presidential race has placed her alongside Vermont Sen. Bernie Sanders and former Vice President Joe Biden in the upper echelon of Democratic candidates, followed up in another tweet on Wednesday.

Before her election to the U.S. Senate, in 2012, Warren was a well-known bankruptcy expert and professor at Harvard Law School. She has for years been critical of the financial industry, ardently opposing a 2005 law that she believed was too favorable to credit card companies and not helpful enough to Americans facing bankruptcy.

"Why not?" Cramer said of increasing the investment income tax rate. "Investment income means you don't do anything. Why is investment income taxed lower than the hard-working people who [make] ordinary income?"

Cramer also said he views Warren's signature wealth tax proposal, which would levy a 2% tax on Americans with $50 million-plus in assets, relatively favorably. Some question both the constitutionality of the proposal and whether it would actually raise the $2.75 trillion over 10 years that her campaign projects.

"Do you think those people would get hurt? I think no," Cramer said. "Those people do great. They can afford it, is what I'm saying."